Oil and vinegar

A clever speculator starts in business with a batch of barrels of oil and vinegar. We do not know how many barrels there are of each but we know that his first client paid $ 14 for each barrel, that he paid double for the gallon of oil than for the vinegar and that he left only one barrel.

What barrel does it leave?

Solution

The customer bought the barrels of 13 and 15 gallon oil at 50 cents per gallon, and the barrels of 31, 18 and 8 gallon vinegar at twenty-five cents per gallon. This leave the 19 gallon barrel , which can contain both oil and vinegar.